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This is a discussion on Nitrite within the Beginner Freshwater Aquarium forums, part of the Freshwater Fish and Aquariums category; --> How can nitrites be elevated when NH3 is 0 and Nitrates are 10-20.If there is NO NH3 present to act as "food" where the ...

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Old 03-24-2012, 01:08 PM   #1

How can nitrites be elevated when NH3 is 0 and Nitrates are 10-20.If there is NO NH3 present to act as "food" where the heck do the nitrites come from??? My idea of the Nitrogen cycle is NH3---NO2----NO3! Thanks

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Old 03-24-2012, 01:59 PM   #2
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Hi Nitrite may also come from organic fish waste one way to get rid of it is having great bio-filtration hope it helps
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Old 03-24-2012, 03:55 PM   #3
Seems like you are in the second part of the nitrate cycle/mini cycle. You are seeing no NH3/4 because the bacteria are all converting it to nitrite. If you added more bioload recently or the tank is not cycled, it may be that the nitrite-converting bacteria are insufficient, you will need to wait until their population is big enough before you see 0 nitrite.

If you are cycling, the nitrates may be from you tap water, if in a mini-cycle, you already have some bacteria producing nitrate.

Anyway, if you have more than 0,3 ppm nitrite, I advise doing a water change, 30-50%, to get it down.
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Old 03-25-2012, 07:55 AM   #4
Nothing new added,no fish, no plants,etc. May have stirred up debris when I did a gravel vac a couple of days before with a 33 1/3 H2O change but that's it.
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Old 03-25-2012, 12:50 PM   #5
You are correct that the nitrogen cycle (or the part we refer to as the cycle) is ammonia -> nitrites -> nitrates (the final step we rarely see is nitrates converted to nitrogen gas by anaerobic bacteria). We most often remove nitrates with routine partial water changes.
Nitrosomonas bacteria oxidize ammonia into nitrites and nitrobacter bacteria oxidizes nitrites into nitrates.
Some think that as soon as they see nitrates, the cycle is complete, however many water supplies have nitrates in the supply water. I just realized that the nitrates in my well water is 60+ppm! I got some 'city' water and found it was 20+ppm in nitrates!
So you should test your tap water. Also just a note, if you are using API's Freshwater Test kit make sure for the nitrate test you really shake the heck out of regent #2 (even knock it against a table) as there is a component that tends to separate and if not mixed well will will often yield a false low reading.

It does sound like you have a good nitrosomonas colony, but the nitrobacter colony isn't quite there yet.
Patience. If nitrates continue to increase, don't be afraid to do a partial water change.

Good luck,
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Old 03-25-2012, 03:16 PM   #6
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I'm surmising from what you have posted that this is not a new tank that is cycling, but one that has been running a while. If this is a correct assumption, then you should never see ammonia or nitrite [once the tank is cycled] as each will be quickly taken up by the bacteria. There are other substrate bacteria that will use nitrate but they are less in number. The nitrate is the end product that is (as someone said) removed via water changes.

You mayfind this article of value in understanding this:
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crs1945 (03-26-2012)
Old 03-26-2012, 08:02 AM   #7
Thanks Byron,

I read your article and I understand it But my question was how can you see a Nitrite spike in a established tank ( that's been running 0/0/5-10ppm readings for months) without seeing a related increase in NH3/4, but with slightly increasing Nitrates? I would expect a spike with a dead fish, much uneaten food, dead plants,etc But I have none of that. It just one day out of the blue spiked to5ppm necessitating a 50% water change followed by a second 50% and we are still at .25 with 0 NH3 and 20-40 nitrates. The nitrates have increases over the last several days.

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Old 03-26-2012, 08:18 AM   #8
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If you live in an area effected by snow during the winter months, then as the runoff and melt begins, many water companies will add extra chemicals to treatment plants to counter act the snow melt water.

It is possible, the spikes you are seeing is caused by that.

Washing of filter media or decorations can sometimes cause a spike as well, if not done in aquarium water.
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Old 03-26-2012, 08:48 AM   #9
I have well water not city.
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Old 03-26-2012, 09:40 AM   #10
I am currently reading Ecology of the Planted Aquarium by D. Walstad and have come across something that might explain what you are currently experiencing.

Walstad argues that another cycle take place in the aquarium : denitrification. It's a process where bacteria, in anaerobic (no oxygen) conditions, take up nitrate, convert it to nitrite, then all the way through to pure nitrogen gas (there are quite a few steps). She points out that incomplete denitrification could cause a Nitrite spike under the right conditions.

Two factors seems to determine if denitrification is to take place. First, since nitrification (the cycle we all know about) is an oxygen-intensive activity : bacteria take up lots of oxygen to convert ammonia to nitrite and then to nitrate. This process can produce some oxygen-depleted (anaerobic) zones in the substrate or immerged filter that promotes denitrification. A second factor seems to be the type and depth of substrate : deep substrate and soil substrate promotes anaerobic bacterial growth, and thus the denitrification cycle.

My guess is that this may be happening in your aquarium. If that's the case, I would think that promoting more oxygenation in the substrate/filter would break the cycle. Also, feeding less may put less demand on oxygen. Walstad argues that the denitrification cycle is completely natural and will eventually balance itself in a planted aquarium. In the mean time, you will see elevated nitrites, wich is not too good for the fishes...
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